Accelerated steel cutting methods and machines for implementing such methods

ABSTRACT

A method for cutting steel includes heating a portion of the steel until it is molten, positioning a cutting torch to have a high angle of incidence relative to the molten steel, and blasting hgih pressure oxygen at the molten metal. The blast of high pressure oxygen further heats the molten metal and blows the molten metal away from the steel to create a cutting trench. The cutting torch is then moved generally parallel to the cutting method includes a cutting torch that emits a high pressure combustible gas and a high pressure combustion enhancing gas. The torch directs the high pressure gases at the steel so that the gases hit the steel at an acute angle of attack. An automated device propels the torch in the general direction of the desired cut. The resultant cut metal product has at least one edge with a grain pattern that is not perpendicular to the direction of cut.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is an application filed under 35 U.S.C. § 111(a)claiming benefit pursuant to 35 U.S.C. § 119(e) of the filing date ofthe Provisional Application No. 60/162,205 filed Oct. 29, 1999, pursuantto 35 U.S.C. § 111(b).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is generally directed to new methods and machinesfor cutting metals, such as steel. More specifically, the presentinvention is directed to a process and apparatus by which steel isquickly cut so as to increase production capacity for steel fabrication,ship building, ship repair and heavy equipment production.

2. Background of the Invention

The traditional method of metal cutting involves the use of cuttingtorches that use oxygen and acetylene gases. The cutting torch operatorsets the oxygen gas pressure level to about 40 to 60 pounds per squareinch and sets the acetylene gas pressure level to about 8 to 12 poundsper square inch. With the cutting torch tip generally perpendicular tothe surface it is cutting, the operator uses the cutting torch to heatthe metal in a local area until it becomes about molten, and thenapplies additional oxygen to heat up the metal even more, therebyreducing the viscosity of the molten metal. With the same oxygen blast,the molten metal is blown out the other side of the metal plate. Withthe torch in a generally perpendicular position, the operator slowlymoves the cutting tip manually along the proposed cutting line. Theprocess of cutting steel is therefore a very slow and tedious process.Metal workers in shipyards, factories, and assembly shops across thecountry spend countless hours cutting steel from steel plate in desiredshapes and sizes.

Conventional flame cutting machines cut with low pressures at relativelyslow speeds. A current “high speed” track torch will cut throughone-quarter inch steel plate no faster than about 24 inches per minute.Usually, the track torch will only be utilized at speeds of no fasterthan 16 inches per minute. Typically, a cutting torch uses oxygen andacetylene at 40 to 60 pounds per square inch and 8 to 12 pounds persquare inch pressure levels, respectively.

In more advanced cutting machines that employ plasma arc cuttingtechniques, the machines are capable of moving up to 70 inches perminute. Although these machines are much quicker than conventionalcutting torch machines, they are complex and very expensive to own andoperate.

Another disadvantage of the current cutting machines and methods is thatthe due to the generally perpendicular positioning of the cutting torchtip or plasma arc tip with respect to the cutting surface, the cuttingtorch tends to cut not only the work piece but also the member thatholds the work piece in place. For example, a steel plate is typicallypositioned on and supported by a cutting table. When the steel plate iscut, the supporting cutting table is also cut because the cutting flamefrom the cutting torch extends through the work piece and into thecutting table. Similarly, when a steel plate is on the side of a ship orattached or welded to a frame or other steel members, the frame or othersteel members are damaged by the cutting torches when cutting the steelplate.

Still another disadvantage of conventional cutting machines and methodsis that portions of the work piece becomes insulated from the heat ofthe flame and flowing oxygen which causes the prior art cutting machinesto lose the cut, slow down, or have imperfect cuts that have to bere-cut. The work piece becomes insulated from the heat due to certainconditions of the metal, i.e., the work piece may be covered or partlycovered with paint, rust or mill scale. Another reason is theoccasionally improper setting of the torch height or heat output, eitherby the operator or by the computer numerical control (CNC).

Throughout the United States and the world, heavy industry has a direneed for faster, cheaper methods and machines for cutting metals inshipyards, factories and steel fabrication lots. As such, a needcurrently exists for an improved method and machine for cutting metal.

In view of the foregoing problems with the conventional art, a needexists for an improved method and machine for cutting metal that isfaster, less expensive, produces a smoother cut, eliminates the problemsof rust, mill scale and paint, and is capable of generally preservingthe structure which supports the work piece.

SUMMARY OF THE INVENTION

The present invention overcomes the foregoing disadvantages ofconventional methods of cutting and provides an inexpensive and improvedapparatus and method for cutting metal that vastly increases the rate atwhich flame cutting of metal can be accomplished.

Accordingly, it is an objective of the present invention to provide animproved method that allows an operator to cut metal at a faster rate.

Another objective of the invention to provide a safe method for cuttingmetal quickly by using two different gases and orienting the cuttingtorch in different cutting positions with respect to an opposing surfaceof a piece of metal.

A further objective of the present invention to provide an improvedmetal cutting apparatus that allows an operator to cut metal at a fasterrate.

Still another objective of the present invention is to provide a methodfor cutting metal at a lower cost.

Another objective of the present invention is to reduce or alleviate theproblems caused by paint, rust or mill scale on a piece of metal.

These and other objectives of the present invention are accomplished byproviding a relatively simple, but unique method for cutting metal thatincludes providing a cutting torch having a tip capable of selectivelydischarging two streams of different gases from two different gassupplies, positioning the cutting torch in opposition to a piece ofmetal and heating a localized area of the metal until it becomes aboutmolten, then positioning the cutting torch such that it is in an angledposition with respect to the piece of metal and increasing the gaspressure of at least one of the two gases to enhance the combustion ofthe first gas and increase the heat directed to the piece of metal,thereby expelling molten metal from the localized area and beyond.

Moreover, the objectives of the present invention are achieved byproviding an apparatus and method for cutting metal that is particularlywell suited for work in and about ships. The process includes, asexemplified in a first embodiment, heating a metal locally to a moltenstate or nearly a molten state, removing the molten metal using a highlypressurized gas, directing the molten metal away from the operator,adjusting at least one of the position and strength of the heat sourceso that the molten metal flows generally away from the operator thusmaking a generally even cut and moving the cutting torch in a directiongenerally parallel to the desired cut line to extend the cut line.

The apparatus of the present invention includes at least one cuttingtorch that uses pressurized gases at high pressure to cut a metalobject. When cutting, the cutting torch has a torch tip which ispositionable at an angle of attack that is less than 90.degree.. Thepreferred range for the angle of attack of the torch tip is about0-45.degree. with a preferred angle range being about 0-10.degree. sothat the tip directs a stream of gas almost parallel with the surface tobe cut. A motive device propels the cutting machine along a desired cutpath to complete the desired cut so that the cutting torch continuouslypreheats and then cuts the metal along the desired cut line.

In yet another exemplary embodiment of the invention at least twotorches are mounted and operated in similar manners and in still anotherembodiment of the invention a cutting torch supplied with pressurizedgases is connected to a multi-jointed arm wherein the cutting torch isrotatable. The cutting torch is connected to a plurality of hingedjoints wherein the base hinge joint is on a pivotal base.

The cutting torch may be connected to at least one ball and socketjoint. In still another embodiment of the invention a cutting torch mayremain stationary while being supplied with high pressure gas and thework piece moves past the cutting torch so that there is relativemovement between the cutting torch and the work piece.

In yet another embodiment of the invention, a plurality of cuttingtorches are connected to a rail so that the distance between cuttingtorches may be adjusted and the cutting torches are also connected to anelevator mechanism so that the height of the cutting torches may beadjusted. The rail is connected to at least one carriage system so thatthe torches and the work piece have relative movement between eachother.

In yet another embodiment of the invention a computerized numericalcontrol (CNC) system is connected to the cutting torches.

The product resulting from the apparatus and methods of the presentinvention is also novel over the prior art. Specifically, a piece ofmetal is shaped by heating a portion of the metal until it reaches amolten state. The portion of molten metal is then removed from the pieceof metal with high pressure gas. The molten metal, when blown by thehigh pressure gas out of a cutting trench, begins to cool. As the moltenmetal cools, it freezes on the metal piece in arcuate or linear shapes.The cut metal is thus distinguishable from the conventional cut metalbecause at least one edge has a grain which is generally parallel, aboutparallel, or diagonal to the edges of the cut.

The present invention is particularly well suited for cutting templatemetal pieces and abstract shapes. The apparatus includes at least onecutting torch that uses pressurized gases at high pressure rates to heatand cut a metal object. At least one cutting torch tip may be operablyconnected to the cutting torch, wherein the tip is positionable at anacute angle relative to the metal. The apparatus may include a motivedevice which causes relative movement between the cutting torch tip andpreheated metal. The motive device propels the cutting apparatus along adesired cut path to complete the desired cut. A high pressurecombustible gas is emitted from the cutting torch tip generally in thedirection of the preheated metal. A high pressure combustion enhancinggas which is emitted from the cutting torch tip and directed generallyat the preheated metal removes the metal from a cutting trench in themetal away from the cutting torch tip.

Additional objects and advantages of the invention are set forth in thedetailed description herein, or will be apparent to those of ordinaryskill in the art. Also, it should be appreciated that modifications andvariations to the specifically illustrated and discussed steps andapparatus parts may be practiced in various embodiments and uses of thisinvention without departing from the spirit and scope thereof, by virtueof present reference thereto. Such variations may include but are notlimited to, substitution of equivalent steps or components for thoseshown or discussed and the reversal of various steps, or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and advantages of the present invention will becomemore apparent by describing in detail preferred embodiments thereof withreference to the attached drawings in which:

FIG. 1 is a perspective view of a piece of metal that has been cut usingthe present invention;

FIG. 2 a is an elevation view taken along section lines I-I of FIG. 1showing an example of a diagonal grain on a work piece cut by thepresent invention;

FIG. 2 b is an elevation view taken along section lines I-I of FIG. 1showing an example of a horizontal grain on a work piece cut by thepresent invention;

FIG. 2 c is an elevation view taken along section lines I-I of FIG. 1showing another example of the diagonal grain of a work piece cut by theinvention;

FIG. 2 d is an elevation view taken along section lines I-I of FIG. 1showing an example of a bi-directional grain of a work piece cut by theinvention;

FIG. 3 a is an elevation view taken along section line II-II of FIG. 3 bshowing a cut edge of a work piece cut by prior art methods or machines;

FIG. 3 b is a top view of a cut work piece cut by a prior art hand heldcutting method;

FIG. 4 is a perspective view of a track cutting torch in accordance withan embodiment of the invention;

FIG. 5 is a perspective view of a self-propelled cutting torch;

FIG. 6 is a perspective view of a robotic arm cutting torch;

FIG. 7 is a perspective view of a single carriage cutting torch;

FIG. 8 is a perspective view of a dual carriage cutting torch;

FIG. 9 a is a diagrammatic view of a shape cutting apparatus;

FIG. 9 b is an electrical schematic of the power system for the dualparallel servo motors;

FIG. 10 is a schematic diagram of a cutting machine with sensors;

FIG. 11 is a perspective view of a plane cutting apparatus;

FIG. 12 a is a perspective view of a cutting torch using the acceleratedsteel cutting method;

FIG. 12 b is a perspective view of a cutting torch in a stop position;

FIG. 12 c shows a cutting torch moving from a stop position in FIG. 12 bto a cutting position;

FIG. 12 d is another perspective view of a cutting torch using theaccelerated steel cutting method;

FIGS. 13 a-13 d illustrate the steps of a method to cut steel accordingto one embodiment of the invention;

FIG. 14 a shows a top view of the method according to the invention toshape a beveled edge;

FIG. 14 b shows an end view of the work piece using the methodillustrated in FIG. 14 a taken along section lines III-III;

FIG. 15 is a cross-sectional view of a method of scarfing or gaugingaccording to the present invention;

FIG. 16 is a perspective view of a piece of gouged metal;

FIGS. 17 a and 17 b are perspective views of metal being cut accordingto the present invention;

FIG. 18 is a perspective view of a cut piece of metal which has been cutaccording to the present invention; and

FIG. 19 is a perspective view of the reverse side of a piece of metalbeing cut according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

U.S. Pat. No. 5,922,144, which is directed to a method for cuttingmetal, is hereby incorporated by reference.

In order to cut metal at a constant rate, several factors must becontrolled. In the present invention, the new position of the cuttingtorch, the higher pressures of the gases, and the different heat createdby burning the combustible gas with high-pressure oxygen, are some ofthe factors which must be controlled. For instance, the angle ofincidence (.alpha..sub.i) of the cutting torch is changed by rotatingthe cutting torch flame from the cutting torch tip about a fixed point.The smaller the angle of incidence, the more heat that is transferred toa smaller, localized area of metal. Heat to an area of metal may also beregulated by moving the tip closer to the metal.

The following discussion is directed to a method for cutting steelaccording to the present invention.

Referring to FIGS. 13 a-13 d, a cutting torch 1000 is used to pre-heatan area 1006 of a workpiece 1010. The cutting torch 1000 may pre-heatthe area 1006 in a number of ways. For instance, the torch 1000 may bepositioned so that an angle of attack (.alpha..sub.2) 1002 equals about90.degree. and an angle of incidence (.alpha..sub.i) 1004 equalsapproximately 0.degree. However, a person having ordinary skill in theart may pre-heat the area in any number of different ways includingwhere the angle of attack 1002 is greater than about 0.degree. and theangle of incidence 1004 is about 90.degree.. This method may be lessefficient; however, it is preferred because the cutting torch does notneed to be repositioned before beginning to cut the metal after it hasbeen pre-heated. Preferably, the area 1006 is heated by holding thecutting torch 1000 above the area 1006 until the area 1006 is aboutmolten. When the area 1006 is about or semi-molten, the work piece 1010which may be metal, preferably a mild steel, is ready to be cut.

A person having ordinary skill in the art is able to determine if thearea 1006 has been preheated enough for cutting. When the pre-heatedarea 1006 is ready to be cut, the cutting torch 1000 is moved into acutting position. A tip 1016 of the cutting torch 1000 should form anacute angle of attack with the work piece 1010. As will be describedbelow, the angle of incidence 1004 and angle of attack 1002 need not bewithin the aforementioned range; however, in order to achieve maximumcutting efficiency, the cutting torch 1000 should be positionedaccording to those angular limits. The angle of attack is generally lessthan about 45.degree.. Alternatively, the angle of incidence 1004 isabout equal to or greater than 45.degree.. In order to increase thecutting rate of the cutting torch 1000, the cutting torch tip 1016 ispositioned at an angle of about 0-10.degree. with the stream of gasflowing generally parallel to the surface being cut.

When the pre-heated area 1006 is about molten, application of additionalcombustion-enhancing gas causes oxidation of the work piece 1010 so thatthe metal turns completely molten. By oxidizing the metal, thepre-heated area 1006 will turn molten. The molten metal may be blownaway from the cutting torch 1000 and the cutting torch tip 1016 (seeFIG. 13 b) as slag 1014. The pressures used to cut and remove the moltenmetal can range from conventional limits for both thecombustion-enhancing gas and combustible gas (for example 50 psi oxygenand 12 psi acetylene) to at least pressures of 300 psi for thecombustion-enhancing gas and at least 150 psi for the combustible gas.The combustion enhancing gas to combustible gases may be mixed inpressure ratios of about 2:1 to 4:1.

The combustion-enhancing gas is oxygen or gases with similar properties.The combustible gas can be any gas, but is preferably an LP gas or gaseswith similar properties. Other combustible gases are well known in theart. Preferred LP gases are propane, propylene, MAPP, natural gas andchemtane mixtures.

Referring now to FIG. 13 c, the cutting torch 1000 moves in a direction1018 to form a cutting trench 1012. At the point where the work piece1010 is to be cut, the thickness of work piece 1010 becomes thinner andthinner. When the cutting trench 1012 is so deep that a remainder 1032is thin enough and molten enough, the high pressure gases from thecutting torch 1000 creates slag 1020 on the side of the metal oppositethe cutting torch 1000. As the cutting torch 1000 moves along thedirection of movement 1018 so as to extend the cutting trench 1012, slag1014 is removed from work piece 1010 from forward edge 1034 of thecutting trench 1012 or some slag 1014 may exit out of the cutting trench1012 on the same side of cutting torch 1000, while the other slag 1020exits on the side of the work piece 1010 opposite cutting torch 1000.Thus, slag may exit either on the same side, the opposite side or onboth sides of the metal as the cutting torch 1000.

As shown in FIG. 13 d, work piece 1010 has a section of cut metal 1022removed from the burning process. Slag 1014 and 1020 are removed fromthe work piece 1010 as the cutting torch 1000 moves in the direction1018 to extend the cut. Slag 1014 exits on the same side of the workpiece as the cutting torch 1000 is positioned while slag 1020 exits fromthe work piece 1010 on the opposite side of the cutting torch 1000. Theamount of slag which exits from each side is dependent upon the angle atwhich the cutting torch tip 1016 is presented to the work piece 1010 andthe viscosity of the slag and the pressure of the gases forcing the slagaway from the work piece 1010.

In another embodiment of the invention, as shown in FIG. 15, the cuttingtorch 1000 may cut a gouge or scarf 1024 in the work piece 1010 usinggenerally the same techniques as described above to cut through a pieceof metal. An operator having ordinary skill in the art will be able toposition the torch and control the intensity and direction of the heatand combustible and combustion-enhancing gases so that the scarf orgouge 1024 may be formed in the work piece 1010. In forming the scarf orgouge 1024 in work piece 1010, the cutting trench 1012 extends onlypartially through the thickness of work piece 1010. Because the cuttingtrench only extends partially through work piece 1010, slag is generallynot blown onto the side of the work piece opposite the cutting torch1000. Scarfing or gouging is used in removing welds or smoothing outplates to take off burrs and the like from the surface of steel.

Another use of the scarfing technique is to remove one piece of steelfrom another piece of steel. This is better illustrated in the exampleof washing an exterior plate from internal framing members on a ship.This technique or process involves removing only one layer of steelwhile the second layer of steel may be left virtually untouched.Scarfing or gouging is well known in the art and may also be used toremove welds so that both the welded piece and welded base remainvirtually intact and undamaged by the cutting method of this invention.During scarfing according to the present invention, a torch operator maymanually move the torch at speeds of about 100 ft/hr while amachine-operated torch can move the torch at faster speeds. The slaggenerally travels on both sides of the cut plate after the cutcommunicates with both sides of the steel plate.

FIGS. 14 a and 14 b illustrate a method of beveling steel according tothe present invention. The new and improved process produces a flatterfinished beveled edge 1028 in a short amount of time.

The work piece 1010 is beveled by an embodiment of the invention whereinthe cutting torch 1000, which may or may not use a beveling tip, ispresented to the work piece 1010 at an angle of attack 1002. Theposition of the cutting tip 1016 preferably has an angle of attackaccording to present invention, as described above. The cutting flameshould be positioned at an uncut edge 1026 so that the angle of thedesired bevel is attained according to known methods. The beveled edge1029 is formed by pre-heating the uncut edge or the corner 1026 of thework piece 1010 and cutting using the above-described method to shapethe uncut edge 1026 into a beveled edge 1028. Slag 1036 exits from thework piece 1010. As the cutting torch 1000 moves along an edge of thework piece 1010, the beveled edge 1028 is formed on work piece 1010using generally the same techniques used to cut or scarf as mentionedabove. The result is a generally smooth beveled edge that is cut quickerthan with conventional methods. Additionally, this technique allows fora hand-held method to be utilized in addition to mechanized methods.

The metal cutting techniques described above can be started from an edgeof the work piece or a middle portion of the work piece. Generally, thesame techniques are used whether starting from the edge of a work pieceor the middle of the work piece. From the edge of the work piece, thearea of the work piece that is to be cut is pre-heated. A person havingordinary skill in the art is able to determine when the pre-heating issufficient by viewing the color of the preheated area or with the use ofsensors. At that time, the flow of the combustion-enhancing gas isincreased so that the metal is oxidized and blown out of the preheatedarea from the cutting trench. This may be accomplished with the cuttingtorch in a variety of positions, from about perpendicular to aboutparallel with the cutting surface as discussed earlier. It is preferredthat the cutting torch is positioned at an angle of attack less than45.degree.; however, the cutting torch may be positioned generallyperpendicularly or with an angle of attack greater than 45.degree..Although these latter angles result in less efficiency, they may benecessary for cornering or moving into confined spaces or other similarsituations.

FIGS. 12 a-12 d further illustrate the method of the present inventionfor moving the cutting torch between angles of attack positions so thatefficiency and precision may be maximized. Referring now to FIG. 12 a, acutting torch 900 moves in a horizontal or x-axis direction 920 so thatan x-axis cut 916 is formed (see FIG. 12 b). The cutting torch 900 hasan angle of attack (.alpha..sub.a) 906 and an angle of incidence(.alpha..sub.i) 904. The angle of attack is less than about 45.degree.,preferably less than 10.degree., to achieve maximum efficiency and mayeven be almost 0.degree. or parallel to the metal surface so that thecutting torch 900 may efficiently pre-heat an area 912 and cut thehorizontal cut 916 so as to remove slag 908 from the cutting trench inthe most efficient manner. Cut length L shows the desired length of cutin a work piece 910.

As shown in FIG. 12 b, the horizontal cut 916 extends to the limit ofthe cut length L for a precise cut. Preferably, the cutting torch 900 ismoved from a preferred angle of attack to a generally perpendicularposition so that the horizontal cut 916 may be more easily controlled tostop at the end of the desired cut length L. The point at which thetorch should be moved from an angle of attack of preferably less than45.degree. to an angle of attack generally about 90.degree. or generallyperpendicular to the work piece 910 depends on many factors includingexperience of the burner, the size of a cutting tip 902, the pressuresof the combustion-enhancing gas and combustible gas, the position of thetorch 900 in relation to a forward edge 934 of the cut 916, the degreeof squareness desired, and the precision of the equipment or operator,among others.

FIG. 12 b shows an example where a high degree of precision is needed,and the cutting torch 900 is moved to a generally perpendicular positionbefore changing directions in the cut. Referring to FIG. 12 c, thehorizontal cut or x-axis cut 916 extends the length L before changingdirections into a vertical cut or y-axis cut 918. If the torch isgenerally stopped at the change of direction point of the cut, then ahigh degree of squareness will be achieved in the cornering. If,however, the horizontal torch is not fully stopped before moving inanother direction, there will be a degree of roundness in a corner 936.In some work a degree of roundness is required. For example, in the shipbuilding industry, a radius is required on many corners. In otherapplications, a right angle is required. As explained above, either maybe achieved by the present invention.

Another way to achieve roundness in corners 936 and 938 is to leave thecutting torch 900 at an angle of attack that is not generallyperpendicular so that the torch 900 traces an arcuate shape. This may bedone, for example, with an embodiment described below and as shown inFIGS. 6 and 7 or in a situation where the torch is mounted to apivotable mount.

Referring now to FIG. 12 c, the cutting torch 900 is moved in a verticaldirection to change the direction of the horizontal cut 916. By movingin a vertical or y-axis direction 922, the cutting torch 900 directs thecutting tip 902 and the flame to a pre-heated area 924, thus creating asmall vertical cut 918. The small cut is defined by the operator whodetermines when to move the tip to a different position. The quicker thetorch is moved from the perpendicular position to an acute angleposition, the faster the torch will cut the metal. An important factorin determining how far to rotate the tip and when to rotate the tip andwhat pressures should be applied is determined by the leading preheatarea 924. When preheat area 924 is heated the torch is moved in thevertical direction and a corner is formed. To increase cutting speed,the cutting torch tip is preferably rotated as illustrated, for exampleby angle of attack 906 in FIG. 12 d. The resulting corners 936 and 938are square. As the vertical or y-axis cut 918 is established and thepre-heated area 924 is ahead of the direction of the cut, the cuttingtorch tip 902 may be moved into a preferred position so that an acuteangle is formed between the tip 902 and the metal to allow for fastercutting.

Referring now to FIG. 12 d, the cutting torch 900 is moved from agenerally perpendicular position to a position with an angle of attack906 or an angle of incidence 904 wherein an acute angle is formedbetween the cutting torch tip 902 and the metal 910. The cutting torch900 may be moved within a plane that contains an imaginary line or a cutline 940 and a perpendicular line 930 of the work piece 910. If thecutting torch 900 is rotated in the imaginary plane containing theimaginary perpendicular line 930 and cut line 940, a cut wall 942 willgenerally be parallel to the perpendicular line 930. If the cuttingtorch has an angle (.alpha..sub..beta.) 944 out of the imaginary plane,then the cut wall 942 will not be generally parallel to theperpendicular line 930. In other words, by adding angle.alpha..sub..beta., the cut wall 942 may have a beveled edge.

When the cutting torch 900 is pivoted in the direction of the pivotarrow 928, the rate of cut of the cutting torch 900 in the direction ofthe vertical direction arrow 922 may be increased because a largerpre-heat area 926 will be formed. Depending on the thickness, thesmaller the angle of attack 906, the faster the cutting torch 900 may bemoved in the vertical direction 922 while still maintaining the cut. Thelimitations of the speed of the cutting torch 900 are dependent uponmany factors including the size of the tip 902, the pressure of thecutting gases, the distance of the cutting torch from the work piece910, the skill of the operator or complexity of the machine and thethickness of the metal. If the work piece 910 is not cut on the firstpass, then multiple passes may need to be made with the cutting torch900 or the cutting torch 900 must be slowed in order to achieve acomplete cut through the work piece. By reducing the angle of attack906, pre-heated area 926 will increase, thus allowing for increasedspeed. However, the pre-heated area should extend through the entiredepth of the cut or else multiple passes may have to be made through thework piece unless a scarf or gouge is desired.

This method of cutting steel, whether by hand or by machine, is idealfor cutting metal that has paint or rust on it. In normal cuttingoperations, paint and rust on the surface of the metal impede thecutting process. With the cutting torch at an angle of attack less than90.degree., the cutting torch is able to get below the paint and rustand cut fresh steel so that the paint and rust is effectively blown awaywith the slag without having to cut through the paint and rust. Thisallows for less restarts caused by popping paint and rust, which canextinguish the flame, or, if an operator is standing close by, causeconcern for safety for the operator which ultimately slows the cuttingprocess. Additionally, many metals are coated with different resins toimpede the rusting process. One advantage of this invention is that itallows an operator using this method to stand away from the actualcutting area so that smoke and fumes from the coatings do not irritatethe operator's eyes, nose, mouth, throat, or skin.

In adapting this method to automated machines, many factors need to becorrelated so that the metal is cut smoothly and efficiently. Whilecutting by hand, an operator is slowed during the cutting process byhaving to reposition himself numerous times in a short period. In orderto cut straight lines while operating a hand-held torch, an operatormust attempt to keep steady and hold a straight line while shufflingpast the metal while keeping the torch on the cut line. Often inrepositioning himself, the operator loses the fluidity of the cut bytaking the torch off the pre-heated area so that he must go back andre-establish his cut after positioning himself before cuttingefficiently again. The operator also cannot cut a straight line using ahandheld torch. With machines, this is no longer a problem becausemotors and engines may continuously drive the machines forward whileholding the cutting torch in a precise position so that the pre-heatedarea is prevented from cooling and the cutting efficiency is maximized,while keeping the torch from diverting from the cut line.

Although the above-described methods for carrying out the presentinvention can be performed manually, an apparatus for maximizing theefficiency and precision of the method of the present invention will nowbe described.

Referring to FIG. 4, a track torch 100 has a torch 140 adjustablymounted to a device body 106. The torch 140 has a torch tip 142 which isselected according to the types and the pressures of gases used, thespeed of the cut desired, the thickness of the metal, and the desiredamount of kerf. Kerf generally refers to the metal loss due to the widthof a cut 116. The torch 140 preferably has a tip number from 00000 to 12in size. Other size tips will work as well. The larger the tip numberthe faster the rate for cutting in a single pass with appropriatepressures; however, the larger the tip, the larger the kerf. The torch140 is supplied with a line of combustible gas 130 and a line ofcombustion-enhancing gas 128. The combustion-enhancing gas is deliveredwithin conventional pressures that can be about 10 psi up to pressuresof at least 300 psi. The combustible gas may be delivered at pressuresas low as 3 or 4 psi up to about at least 150 psi. The gas pressures arerelated to each other, in that too much of a combustion-enhancing gaswill cause the combustion of the combustible gas to cease, whereas toomuch combustible gas will causes a fuel rich mixture and improperresults. The ratio of combustible gas to combustion enhancing gaspressures is from about 1:1.5 to 1:5 and is preferably about 1:2 to 1:3.A person having ordinary skill in the art will be able to mix the gasesin appropriate proportions so that the track torch 100 will operate inan efficient manner. Preferably the pressures of the combustible gas andcombustion-enhancing gas are related to the movement of track torch 100so that as track torch 100 moves the cutting operation may bemaintained.

The torch 140 is mounted on an adjustable arm 146. Preferably theadjustable arm 146 allows the torch 140 to be positioned in a pluralityof positions so that the torch tip 142 may be positioned having an angleof attack that lies between parallel and perpendicular positions withrespect to the work piece. This allows the operator to select theappropriate angle of the cutting torch with relation to the speed of therelative movement of the cutting torch with respect to the work piece114 and the thickness of metal. Generally, the smaller the angle ofattack the faster the track torch 100 will be able to move and stillmaintain the cut. Additionally, the torch 140 is adjustable so that thecutting or torch tip 142 can be positioned closer to or further awayfrom the work piece 114. Preferably the cutting torch is a straightbarrel as opposed to an angled tip, but either will work.

A sleeve 150 holds the torch 140 in place. A torch lock 134 locks theposition of the torch 140 into place with respect to the sleeve 150. Thetorch lock 134 has at least two positions, wherein a first positionallows the torch to be moved with respect to the sleeve 150 so that thedistance between the torch tip 142 and the work piece 114 may be varied.The torch lock 134 has a second position, which prevents relativemovement between the sleeve 150 and the torch 140.

The sleeve 150 is adapted to be connected to a vertical arm 136. Thevertical arm 136 fits within a sleeve 152 so that the distance betweenthe horizontal arm 132 and the torch 140 may be varied. The sleeve 152has a vertical lock 138 that has at least two operable positions. Afirst position. allows relative movement of the vertical arm 136 withrespect to the sleeve 152. In a second position, the vertical lock 138restricts relative movement between the vertical arm 136 and the sleeve152.

The sleeve 152 is operably connected to the horizontal arm 132. Thehorizontal arm 132 is operably connected to a sleeve 154. A horizontallock 126 has at least two operable positions. The first position of thehorizontal lock 126 allows relative movement between the horizontal arm132 and the sleeve 154 It also has a second position that restrictsrelative movement between the horizontal arm 132 and the sleeve 154. Byadjusting the horizontal arm 132 the torch may be positioned closer andfurther away from the track torch 100. The adjustable arm 146 isoperably connected to the track torch 100. In operation, there isrelative movement between the track torch 100 and the work piece 114.The adjustable arm 146 and the torch 140 move relative to the work piece114. Additionally, the adjustable arm 146 may be mounted to the tracktorch 100 through a pivot mount. The pivot mount allows the adjustablearm to be rotated so that the cutting torch 140 may be positioned aroundthe track torch 100.

The track torch 100 preferably has an electric motor 102, which ispowered through an electric cord 104. The electric motor 102 driveswheels 108 so that the track torch 100 may move relative to the track112 and the work piece 114 while the cutting torch 140 makes the cut 116in the work piece 114. The wheels 108 may be connected through casters118 or other drive mechanisms so that the wheels 108 may pivot withrespect to the body 106.

Preferably the track torch 100 rides on a straight track so that thecutting torch 140, when in operation, cuts a straight cut 116 in thework piece 114. Alternatively, if an arcuate shape is desired, the tracktorch will follow the path of an arcuate track and the cutting torchwill be parallel to the movements of the body 106 of the track torch100. Thus, a track of an arcuate shape will result in a cut of anarcuate shape if the torch 140 is held in a fixed position. Gas pressureand torch position adjustments should be made so that the desired cut,gouge, scarf, bevel, or wash cut is maintained.

In order to facilitate the cutting operation, the track torch 100 mayhave pressure control regulators so that the operator can detect thepressures of the combustion-enhancing gas and combustible gas flowing tothe cutting torch 140. A speed control knob 120 is preferably connectedto the track torch 100 so that, based on the pressures of the gases andthe angle of the cutting torch 140, the track torch 100 may move alongtrack 112 at an appropriate speed so that the cutting torch 140efficiently cuts the work piece 114. A switch may control operation ofthe electric motor so that in one position the electric motor engagesthe wheels 108 and the track torch 100 is driven down the track 112 anda second position so that the electric motor is off or disengaged fromthe wheels 108 so that the wheels 108 are not driven by the electricmotor 102. Additionally, a gas cut-off valve can be activated through arelease lever 124 that may be installed to stop the flow of at least onegas to the cutting torch 140. As mentioned earlier, the track torch 100preferably has a supply of combustible gas and combustion-enhancing gas.

In another embodiment of the invention, sensing mechanisms may be addedto the track torch so that if a desired cut is lost or about to be lostthe track torch slows itself so that either the cut is reestablished orthe operator is notified of the lost cut and can make the necessaryadjustments. Such devices are well known in the art and are disclosed inU.S. Pat. No. 2,514,302 which is herein incorporated by reference, aswell as others discussed below.

In operation, a person having ordinary skill in the art will set up thetrack 112 in a desired position and place the track torch 100 on thetrack 112. The operator positions the work piece 114 at a desirabledistance away from the track 112 so that the torch 140 will cut the workpiece 114 along a desired path. Preferably the operator will adjust theposition of the torch on the adjustable arm 146 so that a desired cutmay be made. The operator positions the angle and the distance betweenthe torch 140 and the work piece 114. Based on these adjustments, theoperator will adjust the speed of the track torch 100 relative to thework piece 114 so that the position of the torch 140, the speed of thetrack torch 100 and the gas pressures cooperate so that a cut in thework piece 114 may be made. Any further adjustments to the track torchor speed can be made when the cutting torch is ignited to preheat thecut 116. Upon proper pre-heating, the electric motor 102 will be engagedso that the wheels 108 propel the track torch 100 down the track. As thetrack torch 100 is propelled down the track, the cutting flame 148 cutsthe work piece 114 with high pressure combustible and combustionenhancing gases so as to cut the metal at speeds preferably greater thantwo feet per minute up to speeds of at least 30 feet per minute. Inorder to ensure an efficient cut, the operator selects a speed, gaspressures, position of the torch tip size corresponding to the thicknessof work piece 114, and the desired curve or lack thereof. A personhaving ordinary skill in the art will be able to increase the maximumtrack torch speeds from about 16 inches per minutes to speeds of atleast about 30 feet per minute with a preferred track torch speedbetween about five and twenty feet of cut per minute.

In another embodiment of the invention as shown in FIG. 5, aself-propelled cutting torch 200 can be used to cut metal using thetechniques described herein. The self-propelled cutting torch 200 has abody 106 that is connected to wheels 206 which are driven by an electricmotor 102. The combustion-enhancing gas 128 and combustible gas 130 aresupplied to the self-propelled torch 200. An adjustable torch 202 isrotatable about a pin 210 and the distance between a cutting tip 216 anda work piece 114 may be adjusted by moving the pin 210 between pinopenings 208. Thus, an angle of attack may be adjusted from about0.degree. to about perpendicular with the work piece 114 and anadjustment lever 218 may be used to position the adjustable torch 202 atan appropriate angle of attack and distance between the cutting tip andthe work piece 114. The adjustable torch 202 is mounted to the body 106of the self-propelled cutting torch 200 by a cantilever frame 214.

In order to propel the self-propelled cutting torch 200, an electricmotor operably engages the wheels 206. The wheels 206 frictionallyengage with the work piece surface 220.

The self-propelled cutting torch 200 may also be attached to preferablyangled or vertical surfaces through a magnetic system that is wellknown. The magnetic system causes the self-propelled torch 200 to adhereto the work piece 114, for example, the side of a ship; however,movement of the self-propelled cutting torch 200 with respect to thework piece still occurs so that the cutting torch 200 cuts the metal.Magnetic attachment systems are disclosed in U.S. Pat. Nos. 5,562,043and 5,811,055 that are herein incorporated by reference. In anadditional embodiment of the invention, the self-propelled cutting torch200 may have a mechanical device to allow it to turn as in U.S. Pat. No.5,693,286 which is also incorporated herein by reference. In stillanother embodiment of the invention, any of these embodiments may beequipped with an automatic lighting system as disclosed in U.S. Pat. No.4,433,358 which is herein incorporated by reference. In yet anotherembodiment of the invention, this device may be used to cut bevelededges on pipes in a method disclosed in U.S. Pat. Nos. 4,202,535 and4,135,701 that are herein incorporated by reference.

Referring now to FIG. 6, a robotic arm cutting torch 300 cuts a piece ofmetal. The robotic arm cutting torch 300 has a plurality of segmentsinterconnected to a base 312. The base 12 is preferably connected to therobotic arm by a base rotator 314 that can rotate about 360.degree. fora full range of motion. In another embodiment, the robot arm isconnected to a motive device like a tracked vehicle. A robotic armsegment 316 is connected to the base rotator 314 at a first end througha robotic arm hinge 318. On a second end of the robotic arm segment 316,a robotic arm segment 326 is connected to the robotic arm segment 316,so that the robotic arm segment 326 may pivot about 360.degree. about arobotic arm hinge 324. The robotic arm segment 326 is connected on asecond end to a robotic arm hinge 322. The robotic arm hinge 322 isconnected to a robotic arm segment 328 on a first end so that therobotic arm segment 328 may pivot approximately 360.degree. about therobotic arm hinge 322. The robotic arm segment 328 is connected on asecond end to a rotatable head 320. The rotatable head 320 can movepreferably about 360.degree. so as to rotate cutting torch 110 to anyposition. The cutting torch 110 is connected to combustion-enhancing gasand combustible gas lines 128 and 130. Additional segments can be addedto the robotic arm cutting torch as needed so that movements of therobotic arm are fluid and that the robotic arm may reach any position ofa work piece placed on a cutting table 310. The cutting table 310 issupported by table legs 306. A robotic arm control system 304 is wellknown by a person having ordinary skill in the art. The control system304 is preferably a microprocessor, a personal computer, or a CNCmachine. Preferably, the control system 304 is a CNC machine which cancontrol all the movements of the robotic arm cutting system includingsegments 316, 326 and 328 as well as the cutting torch 110 so thatcutting torch 110 may be moved from an about perpendicular position witha surface 308 of the cutting table 310 to an about parallel positionwith the work piece. With a jointed arm as shown in FIG. 6, the roboticarm cutting torch may cut steel according to a preferred embodiment ofthe invention. The robotic arm cutting torch may have at least one balland socket joint to give a different range and fluidity of motions.

The control system 304 is capable of controlling the robotic armmovements as well as regulating the pressures flowing through thecombustion-enhancing gas line 128 and the combustible gas line 130 sothat pressures may be varied over the entire disclosed range as neededby the cutting torch in making its variety of cuts. By regulating thepressures in conjunction with the movements of the robotic arm, thecontrol system 304 can maintain a cut while increasing cutting speed orprecision. The control system 304 is preferably capable of moving thecutting torch tip from a vertical position wherein more control of thecut may be had, to a generally horizontal position where the cut in theworkpiece made be made faster with straight line cuts. Additionally, therobotic arm may pick up different cutting devices so that it may performgouging, cutting or beveling in a more efficient manner. Preprogrammedpatterns may be input into the control device so that the robotic armwill trace or cut a pattern in the work piece. A person having ordinaryskill in the art will be able to program the control device so that therobotic arm cutting torch 300 will change the position of the cuttingtorch 110 to make sharp corners, straight cuts, or rounded arcuateshapes. Additionally, sensors may be added to the robotic arm cuttingtorch 300 to form a feedback loop so that the control system candetermine whether or not a good cut was made into the work piece andwhether or not to slow down, speed up or repeat any portions of thecutting program. The sensors will be discussed in more detail below.

As shown in FIG. 7, a single carriage cutting torch 400 moves along acarriage track 406 on the cutting table 310 supported by the legs 306and with the support surface 308 for the work piece. The single carriagecutting torch 400 is mounted on a plurality of carriage wheels 404 thatride along carriage track 406. At least one carriage motor 412 isattached to a single carriage cutting torch. Preferably one carriagemotor 412 is attached to each side of the single carriage cutting torch400. By attaching one carriage motor 412 on each side and coordinatingthe movements through a control system, torsion created by driving thesingle carriage cutting torch on only one side is avoided. The singlecarriage cutting torch 400 has at least one carriage 402 driven by acarriage motor 412 to propel it up and down carriage track 406 creatingrelative movement between the carriage cutting torch 400 and a workpiece 424. The carriage 402 is connected to a carriage frame 414. Thecarriage frame 414 is connected to a beam 416. The beam 416 isoperationally configured to a support elevator 418. The elevator 418 cantraverse the length of the beam 416 on beam traverse mechanism 420. Anelevator mechanism 422 elevates and depresses the elevator 418 thuspositioning the cutting torch 110 closer or further away from the workpiece 424. A hinge 426 is operably connected to the elevator 418 andcontrolled by a control system so that the elevator segment 428 which isconnected to the elevator 418 through hinge 426 can move from a firstposition 408 into a second position 410 depending on the programming ofthe control system and the method used to cut the work piece 424. Theelevator segment 428 is mechanically connected to the cutting torch 110through a rotatable head 320. The rotatable head 320 allows the cuttingtorch 110 to pivot through 360.degree.. In an alternative embodiment ofthe invention, the hinge 426 or rotatable head 320 is replaced with aball and socket joint.

The single carriage cutting torch is preferably designed for straightline cutting for cuts parallel to carriage tracks 406 and for cutstransverse to carriage tracks 406. Additionally, the single carriagecutting torch may corner and create arcuate shapes by having a controlsystem operate the beam traverse mechanism and carriage motor 412generally simultaneously. For example, as the single carriage cuttingtorch 400 moves up and down along carriage track 406, movement by thebeam traverse mechanism 420 will create an arcuate shape. Similarly,while the cutting torch is moving along beam traverse mechanism 420, ifthe carriage 402 moves, then an arcuate shape may be created. One way toprevent an arcuate shape is if the carriage 402 or beam traversemechanism 420 comes to a complete stop before the other one is operated.By moving the cutting torch 110 while coordinating carnage andtransverse movement, arcuate shapes are easily formed.

In another embodiment of the invention as depicted in FIG. 8, a dualcarriage cutting torch may be provided. A x-direction cutting torch 502and a y-direction cutting torch 504 are generally similar to the singlecarriage cutting torch described above. Both torches 502 and 504 move onat least one carriage 402 which has a carriage motor 412, and wheels 404which ride upon carriage track 406. The carriage 402 is connected to aframe 414 that is connected to a beam 416: The elevator 418 isoperationally connected to the beam 416 and the beam traverse mechanism420 so that the elevator 418 may move across the length of the beam. Theelevator 418 may be raised and lowered so that the cutting torch 110 israised and lowered closer or farther away from the work piece 424. Theelevator mechanism 422 controls the vertical movement of the elevator418. The elevator 418 is connected to the cutting torch 110 preferablythrough a hinge 426 or ball and socket mechanism so that cutting torchmay be moved between a generally low angle of attack to a generally highangle of attack. The cutting torch 110 is operationally connected tocombustion-enhancing gas source 128 and combustible gas source 130.

The dual carriage cutting torch system is optimally designed forbi-directional cutting. One cutting torch, the y-direction cutting torch504, would preferably make all cuts parallel with the cutting track.Whereas, the x-direction cutting torch 502 would make all cutstransverse to cutting track 406. If any arcuate shapes needed to be madein work piece 424, either torch 502 or 504 would be capable of makingthose arcuate cuts.

The control system for this automated cutting torch would be similar tothe control system of the single carriage cutting torch except that acontrol system would have to coordinate the movements of two cuttingtorches which would require special attention whenever one passed theother. In the alternative embodiment of the invention, both cuttingtorches 502 and 504 could cut both in the x-direction and in they-direction; however, the control system would have to coordinate theirmovements so that the torches did not have conflicting paths whencutting. The coordination of multiple torches is well known in the art.

Referring now to FIGS. 9 a and 9 b, illustrated therein is a preferredembodiment of a shape cutting apparatus 600 which includes a pair ofcarriages 402 which will be described in greater detail herein below.The wheels 404 are provided with the carriages 402 with such wheelsbeing mounted for translation along the rails 406. The transverse beam416, which is rigidly mounted on extended cross carriages 402, includesa bridge portion 604 and a cantilever portion 606. Torch holderassemblies 608 which may include conventional devices for supporting aplurality of oxygen-fuel cutting torches 110 above a metal plate 610 aremounted for translation along the length of the transverse beam 416. Aservo motor 612 is provided to drive a tracer holding assembly 614 inresponse to signals provided from a control device 616 and a servoamplifier 618.

In addition, a suitable hose assembly 602 is adapted to supplycombustion enhancing gas, preferably oxygen, combustible gas or fuel,and any necessary coolant to torches 110 and is connected between suchtorches and the control device 616 and a gas control panel 620. The gascontrol panel 620 may be used to effectively regulate the pressures ofthe gases so that the machine can cut at high speeds in accordance withthe preferred embodiment of the invention and may display a readout sothat an operator may monitor them. A tracing assembly 622 is mounted onthe cantilever portion 606 of the transverse beam 416 and is effectivein a known manner to follow a line or edge on a template or pattern (notshown) positioned there below. The tracer holder assembly 614 ispreferably mechanically connected to torch holder assemblies 608 bymeans of a band 624, which extends over the whole length of beam 416 andis driven by pulleys (not shown) in a conventional manner. The tracingassembly 622 is connected by a line 626 to the servo amplifier 618. Itwill be understood by a person having ordinary skill in the art that thetorch holder assembly 608 may include means for raising and loweringtorches 110 and further description thereof is not considered necessary.The torch holder assembly may also pivot so as to change the angle ofattack between the cutting torches and the workpiece, i.e., metal plate610.

In another embodiment of the invention, the torches may be rotatableabout the transverse beam 416 so that the torches can cut the metalplate 610 at high speeds using high pressure combustible gas andcombustion enhancing gas. By having cutting torches 110 repositionablebetween a high angle of attack and a low angle of attack with the metalplate 610 in conjunction with high pressure gases as described herein,faster cutting speeds may be achieved than previously attained withsimilar machines using low pressure gases which are typically 20 psi and60 psi for combustible and combustion enhancing gases, respectively.

Dual side drive servo motors 628 are mounted on the carriages 402respectively, and are effective to drive the wheels 404 along the tracks406, in the longitudinal direction of travel of apparatus 600. The servomotors 628 are connected through resistances R in parallel with oneanother and across a source of electrical potential E as indicated inFIG. 9 b. The connection is shown by means of connecting line 630 ofconnecting motor 628 to servo amplifier 618 which in turn is connectedthrough line 632 to control device 616. The servo motors 628 arepreferably coupled to the wheels 404 by suitable reduction gearing wellknown to those skilled in the art.

In operation, the tracing assembly 622 on the cantilever portion 606 ofthe beam 416 will begin to follow a line or edge on a template (notshown) and is effective to generate electrical signals representative ofthe position of such line or edge. The signals are supplied over a line626 to the servo amplifier 618 after which the torches 110 are ignited,and will supply electrical signals to the servo motors 612 therebydriving the transverse beam 416 in a longitudinal direction and thetorch holder assembly 608 in a transverse direction at a ratecorresponding to the velocity of the tracing head 622 thereby causingthe torches 110 to cut patterns in the plate 610 identical to thepattern or template followed by the tracer head 622. The cutting torchesmay be operated in a range of positions from either a generallyperpendicular position through a generally parallel position relative tothe metal plate 610. As the cutting torches move from the generallyperpendicular position to the generally parallel position and/or as thegas pressures are increased to the torches 110 in accordance with theherein described method, the tracing head 622 may accelerate to fastertracing speeds. The cutting torches may be operated in unison or theymay be operated independently. The torches can be started and stopped asnecessary to get the required trace pattern.

In another embodiment of the invention, at least one sensor may beplaced about a cutting torch so that a control device may determine ifthe tracing head 622 may accelerate and maintain higher velocities intracing its pattern and still maintain its cut. If the tracing head 622encounters a corner or curvature, the cutting torches may be controlledto follow the curvature on the metal plate 610. If the tracing head 622encounters a curvature or corner, the cutting torches may be rotated.The mechanisms which allow this are well know in the art. In anotherembodiment the torches may be moved from a relatively small angle ofattack to a comparatively greater angle of attack or vice versa. As thetorches are moved the cutting speed of the torches will be slowed and acorresponding slowing of the carriages would preferably ensue. As thecutting torches finish the curvature and move to straight line cutting,the torches may then be moved to a relatively smaller angle of attackand the carriage devices accelerated to correspond with the new rate ofcut by the cutting torches. The pressures of the gases may also bevaried to better control the cut.

By utilizing the dual side drive servo motors 612 connected electricallyand in parallel with one another, the transverse beam 416 is maintainedin a square relationship with the carriages 402 and thereby enables thetracer head 622 to negotiate corners at a greater velocity for the sameradius of curvature which is obtained by a single side drive systemsonly at substantially lower speeds. In an alternative embodiment of theinvention a single carriage may be used to drive this mechanism. U.S.Pat. No. 4,194,727 is herein incorporated by reference.

In FIG. 10, a cutting mechanism has a sensing device attached such asone disclosed in U.S. Pat. No. 5,470,047, which is herein incorporatedby reference. A gas accelerated steel cutting apparatus with a sensor700 comprises a cutting mechanism 714 which incorporates the acceleratedsteel cutting method described herein above, the cutting mechanismdriver 712, a flame sensor 722, a microprocessor for control system 724and input-output devices 732 and 738. Other sensors such as positionsensors, temperature sensors, and pressure sensors are well known in theart and may be used to better control any of the herein describedcutting machinery.

The cutting mechanism 714 includes a main body 702 having a guide member704 at its upper portion, a first slider 706 movable along the guidemember 704 to and fro, a second slider 708 movable along the firstslider 706 in the direction of the right and left, and a torch 710movable through the first and second sliders 706 and 708 upwardly anddownwardly. The first slider 706 preferably has an articulated member740 for adjusting the angle of the torch 710 so as to form an angle ofattack with a work piece, i.e., a metal sheet 720. The metal sheet 720is located under a tip portion 716 of a torch 710 on a bed 718. Thecutting torch 710 is at an angle of attack between about 0 and about90.degree. so as to cut the metal sheet in accordance with the presentinvention.

These components of the cutting mechanism 714 are driven by theconventional cutting mechanism driver 712 which is responsive to controlsignals provided by the microprocessor 724 and may include a hydraulicsystem or a servo system actuated by an electrical control signal.

The flame sensors 722 detect the current flow through a flame formedbetween the torch 710 and the work piece 720, and generate a currentsense signal which represents a voltage corresponding to the detectedcurrent and is coupled to the microprocessor 724. The microprocessor 724can include a central processing unit (CPU) 726, a read only memory(ROM) 728, a random access memory (RAM) 730, and input-output (I/O)interface 734 and analogue digital (A/D) converter 736. The CPU 726receives a current sense signal through the A/D converter 736 coupled tothe I/O devices, e.g. computer aided design (CAD) system 732 and acontrol console 738 via the I/O interface 738. The CAD system 732 and acontrol console 738 via the I/O interface 734. The CAD system 732 andthe control console 738, which are well known in the art, serve togenerate cutting contour information and user setting information,respectively. The CPU 726 which is coupled to the cutting mechanismdriver 712 via I/O interface 734 serves to receive the cutting contourinformation and the user setting information and to generate the controlsignal. The I/O interface may include a plurality of photo couplers (notshown) to serve to electrically isolate the microprocessor 40 from thecutting mechanism driver 712 having a high voltage drive source.

The microprocessor 724 has a numerical control function to controlvarious operations of the gas cutting machine including discharging acombustible gas and a combustion enhancing gas at specific pressures toform a flame, controlling the torch home position, and controlling themovement of the components of the cutting mechanism 714 in accordancewith the cutting information inputs from the CAD system 732 and thecontrol console 738. The control console 738, as is well know in theart, may include a monitor and a keyboard for user interfacing. Themicroprocessor can control the position of the cutting torch withrespect to the work piece 720. The cutting torch position can be simplydetermined by x-axis, y-axis and z-axis coordinates given by positionsensors. The angular position of the cutting torch 710, including theangle of attack of cutting torch 710, may be controlled by themicroprocessor 724. The microprocessor may also control gas pressures tothe cutting torch, relative movement between the cutting torch and thework piece, complex linear and arcuate cutting patterns, ignition andextinction of the cutting flame, addition and removal of work pieces,the changing of the cutting tip and the changing of tools so thatdifferent cutting torches or tools may be connected to this mechanism toperform work on the work piece 720. It is well known in the art tocontrol at least these actions as well as sensing the temperature andrate of cut of the cutting device through the microprocessor 724.

To start a cut at the edge of work piece 720, the preheat flame may beplaced just about over the edge to heat the work piece 720. Preferablywhen the work piece 720 is heated to an about molten state, thecombustion enhancing fuel is increased, and the torch 710 moves over thework piece 720. Therefore, the combustion enhancing gas cutting isaccomplished through the use of the chemical reaction in which thepreheated metal is cut, or removed by rapid oxidation in a stream ofoxygen.

During the cutting operation, the combustion enhancing gas andcombustible gas preferably flow through separate channels to the cuttingtorch 710 at pressures controlled by a pressure regulator (not shown) inaccordance with the herein described method, which is provided in thecutting mechanism 714 and may be adjusted by the operator. The channelscontrolled by the pressure regulator serve to supply a gas mixture of aproper ratio for preheating and a high pressure gas stream for cuttingto the torch tip portion. By adjusting or controlling the flow rate inthe channels from the microprocessor 724, the operator can set theprecise gas mixture desired. For machine cutting, gases are normallycontrolled by numerical control.

Alternatively, a pressure sensing mechanism, which is well known in theart, may be attached to the accelerated flame cutting machine. Thepressure sensing device feeds information to the microprocessor so thatthe microprocessor may adjust the position of the cutting torch relativeto the work piece to allow for the most efficient cutting. Other sensingdevices, for example temperature control, may also be used to improvecutting performance.

An accelerated flame cutting machine may also be provided having a CNCcontrol with programmable memory wherein the memory is programmed tocause automatic cutting of pieces continuously in succession, andwherein the memory also includes selectively actuatable instructions tocontrol the torches so that beveling, gouging or cutting may beperformed. Additionally, a CNC control system would be useful inreestablishing a lost cut, as described in U.S. Pat. No. 4,466,069 whichis herein incorporated by reference.

A CNC is of any well known type which is conventional in the metalcutting field and includes, among other things, a programming devicewhich may include paper, magnetic tape or other data storage deviceswhich pass over the usual pickup head section which in turn inputs tothe memory unit of the CNC. See U.S. Pat. Nos. 4,014,495 and 4,121,808for further details relative to the programmable numerical controldevices. Those patents are herein incorporated by reference.

FIG. 11 shows an embodiment of the invention with an accelerated flamecutting apparatus 800. The flame cutting apparatus 800 has a bridgeportion 802 that is suspended between two support gantries 804. Each ofthe support gantries 804 is mounted for movement along rails 810 so thata bridge portion 802 will pass over the top of a cutting table 806.

Also secured to the bridge portion 802 are a plurality of flame cuttingassemblies 814 for use with the present invention. They are mounted forcontrolled movement laterally across the bridge. There are severalconventional means of moving the flame cutting assemblies 812 across thebridge 802, such as a rack and pinion, an axially threaded rod withfollowers, or an endless steel band, all of which extend the length ofthe bridge and are controlled by gear motors which permit accuratepositioning of the flame cutting assemblies 814 anywhere along thebridge member 802 in a manner well known in the art of numericallycontrolled flame cutting apparatus.

Motors that operate the traversing mechanism are controlled by thenumerical control equipment. An input control panel 816 is generallyused to program and operate the numerical control equipment so that thecutting assemblies 812 will move in a desired pattern. The flame cuttingapparatus 800 illustrated in FIG. 11 is merely an example of the type ofmechanism to which the accelerated steel cutting technology and methodmay be incorporated. The cutting table 806 may be conventional and canvary in design. It is usually a plurality of spaced parallel barsrunning transversely parallel to the bridge 802 longitudinally parallelto the rails 810. Another type of conventional cutting table consists ofa plurality of pointed members extending vertically upwards so as tosupport the work piece in a horizontal position. Some spacers areusually provided between the support members forming the cutting table806 and the bottom of the work piece since the flames from the cuttingassemblies 812 often pass through the work piece. However, with themethod and apparatus of the present invention, the flame does not cut asdeeply as conventional cutting methods due to the angle of attack thusallowing a longer life for the cutting table, which further reducescosts.

FIG. 16 shows a product resulting from the present inventive method andapparatus. FIG. 16 shows cut metal 1100. The metal, even if heavilypainted or rusted, may have a scarf or gouge 1118 formed therein. Thegouge is formed by pre-heating the metal 1100 to an about molten stateand applying high pressure gases to the about molten metal so that theabout molten metal becomes fully molten and can be blown out of acutting trench 1116 about a cut line 1112. The scarf or gouge 1118 isformed by moving the cutting torch at an angle of attack generally lessthan about 45.degree.. The cutting torch is moved relative to thesurface of the cut metal 1100 so that the scarf or gouge 1118 is formedin the cut metal 1100 at the appropriate depth. A smaller angle ofattack results in a shallow gouge, while a big angle of attack resultsin a deeper gouge. The scarf or gouge 1118 is made in the metal 1100 byadjusting at least one of: the angle of attack of the cutting torch; thepressures of the combustion enhancing gas and/or combustible gas; theangle of the cutting torch and the distance between the cutting torchand the cut metal.

The scarf or gouge 1118 is characterized by a plurality of arcuate marks1114 positioned generally transverse to cut line 1112. The arcuategrooves result from changes in the metal, adjustments in the rate ofspeed of the torch movement along the cut line 1112, changes in gaspressure, changes in the angle of attack of the cutting torch, and thedistance between the cutting torch and the cut metal 1100.

As the cutting torch moves along cut line 1112, hot slag is pushed upand out of cutting trench 1116. The slag is pushed forward by the highpressure combustion enhancing gas so that a pool of hot slag is drivenbefore the cutting torch. As the hot slag accumulates, the hot slag isblown away from the cutting trench by high pressure gas in accordancewith the herein described method. As the combustion enhancing gas blowsthe hot slag in front of it, gravity, gas direction, pressure, and metalshape affect the hot slag to change the velocity and direction of thehot slag. As the slag is pushed out of the way of the combustionenhancing gas, the ambient air and torch gases, as well as the heattransfer properties of the metal, cool the hot molten slag thus causingit to solidify into a generally solid state on the metal. The resultingproduct is a piece of cut metal 1100 with a gouge or scarf 1118 formedthereon with cooled slag tracks generally emanating from the scarf orgouge 1118 formed in a generally arcuate 1110 or linear shape.

The slag, if on a painted or rusted surface, is relatively easy toremove and can be scraped off often with a gloved hand or the back of acutting torch. Additionally, the slag may be removed with a grinder andother methods known in the art.

Not all slag is blown out of the cutting trench and left to reform onthe metal. Due to gravity and the high pressure combustion enhancinggas, a lot of slag is blown away from the cut metal 1100. The scarf orgouge 1118 formed by a machine is characterized as being mechanicallyformed. This is in contrast to a hand held scarf or gouge wherein thesides and/or depth of gouge deviate because of the operator holding thecutting torch. By having the machine at least hold, if not control, thecutting torch, uniform cuts, gouges, and bevels are made. The cuts,gouges and bevels are not only consistent throughout their length (ofcourse there are minor deviations in even a mechanical cut) but are alsogenerally consistent from work piece to work piece if the mechanicalsettings are the same on the machines and the deviations resulting fromthe steel and environment are ignored.

Referring now to FIGS. 17 a and 17 b, a similar freezing process happenswhen the cut extends completely through the metal as opposed to a gougeor a scarf in FIG. 16. Cut metal is formed by a cutting torch with flame1106 applying heat to make the metal 1100 about molten. As the moltenmetal is blown with high pressure gases, the about molten metal turnscompletely molten and is pushed ahead of the high pressure gases. Hotslag is blown off the metal 1100 and generally flows away from highpressure gases. As hot slag 1108 pools in front of the gas, the hot slagaffected both by gravity and the gas pressure, moves away from a cutline 1112 forming an arcuate path 1122 or a linear path. If the piece ofmetal on one side of the cut line 1112 is small enough, the metal warpsaway from the cut line forming warped metal 1104. Some of the hot slag1108 will come off in a pool or a stream whereas other pieces of hotslag are blown away as small semi-molten or molten beads or drops 1126.FIG. 17 a shows the back side of metal 1104 cut by the presentinvention. FIG. 17 b shows the front side of the metal 1104.

Referring now to FIG. 18, cut metal 1100 is shown after all the moltenmetal has cooled and solidified again as solid metal, and cooled slag1110 is formed about imaginary cut line 1112. When the cut metal 1100 iscut all the way through it thickness, rounded edge linear grooves 1121on rounded edge 1120 may be formed along the walls of the cutting trench1116 about the cut line 1112. The kerf 1102 of cut line 1112 is thewidth of metal that is removed as a result of the cut. On a paintedsurface, the cooled slag generally does not completely adhere. The sameis generally true for a rusted surface. However, when the steel is cleanor new, the cooled slag generally tends to adhere relatively more to theclean or new steel. Often the cooled slag 1110 may be removed with agloved hand, a scraping device or the back of the torch. In either case,grinding removes the steel from the surface. This improves the clean uptime needed to prepare the metal for welding or painting.

Referring now to FIG. 19 which shows the back side of a piece of steel,one can see that slag may come off the back side when a cut goes throughboth sides of the cut metal 1100 The same arcuate paths 1122 and themolten beads 1126 come off the back side but are generally less involume than on the front side. Due to the high pressure, the moltenmetal, which forms part of the side of the cut metal 1100 furthest awayfrom the cutting torch, is blown out on the back side when the metalbecomes molten and in contact with the high pressure gases as describedherein above.

Referring now to FIG. 1, a work piece 1200 is shown cut in two piecesabout a cut line 1210 by a machine described hereinabove. The work piecehas two sides 1220 or surfaces. An edge 1212 connects the two sides1220. The separation difference between the cut edges of work piece 1200is the kerf 1218. The kerf 1218 as described above is determined by amultitude of factors so that the kerf can be maximized or minimized asthe situation dictates. It also should be noted that cut edge 1212 isapproximately straight. An operator may induce a slight bevel 1214 onthe edge 1212. The extent of the bevel is determined by the many factorsincluding torch position, torch tip size, angle of attack, gaspressures, and speed of the cut. The edge 1212 typically has a visiblegrain pattern; however, in certain situations there is no visible grainpattern on the edge 1212.

FIGS. 2 a-2 d show the cut edge face 1216 taken along section lines I-Iof FIG. 1. FIGS. 2 a-2 d show possible grain patterns in the cut metal1200 using the present invention. The product shown in FIGS. 1-2 d isdistinguishable from the prior art product shown in FIGS. 3 a-3 b.

In the present invention an operator can produce a diagonal grain 1304or 1308 (see FIGS. 2 a and 2 c). The grain is on a diagonal because thecutting torch is positioned above the workpiece 1200 and the cuttingtorch flame is at an angle of attack as disclosed by the presentinvention. The angle of the diagonal grain 1304 and 1308 will depend onmany factors including the angle of attack, the gas pressures, the tipsize, the thickness of the metal, the type of metal, the speed of thecut and the distance between the cutting tip and the metal. In certainsituations, typically when gas pressures are high and the pressurizedgases are directed about parallel to the cut edge, a parallel grainpattern 1306 will be formed on the cut metal piece (see FIG. 2 b). Theparallel grain pattern 1306 is generally parallel to the edge 1212.Alternatively, a divergent grain pattern 1310 may be formed as shown inFIG. 2 d.

In contrast, the prior art grain pattern 1302 shown in FIG. 3 a isperpendicular to the side 1220 because the cutting torch of the priorart directs gases perpendicular to the direction of cut. One of the maindrawbacks in using the prior art cutting methods, especially when handheld, is that an uneven edge 1312 is formed as shown in FIG. 3 b. Thus,the present invention provides for a much smoother edge. Additionally, astraighter edge may be formed using these devices than with either ahand held method or conventional machines. In yet another embodiment ofthe present invention, edge 1212 may be rounded 1120 as shown in FIG.18, as opposed to the angular edge 1212 shown in FIG. 1.

It should be further understood by those of ordinary skill in the artthat the foregoing presently preferred embodiments are exemplary onlyand that the attendant description thereof is likewise by way of wordsan example rather than words of limitation, and their use does notpreclude inclusion of such modifications, variations and/or addition tothe present invention as would be readily apparent to one of ordinaryskill in the art, the scope of the present invention being set forth inthe appended claims.

1-20. (canceled)
 21. A piece of cut metal formed by a metal cuttingapparatus, comprising: a metal base having a first surface and a secondsurface disposed on opposite sides of said metal base; an edgeconnecting said first and second surfaces, wherein said edge has a grainpattern that is not perpendicular to said first and second surfaces; andcooled slag semi-adhering to the metal base wherein the cooled slagforms a plurality of generally arcuate paths.
 22. A piece of cut metalaccording to claim 21, wherein said slag is disposed on the firstsurface and wherein the metal cutting apparatus is located on a side ofthe metal where the slag is located.
 23. A piece of cut metal accordingto claim 22, wherein the edge is beveled.
 24. A piece of cut metalaccording to claim 21, wherein the edge is rounded.
 25. A piece of cutmetal according to claim 21, wherein said slag is disposed on the secondsurface and wherein the metal cutting apparatus is located on a side ofthe metal opposite where the slag is located.
 26. A piece of cut metalaccording to claim 25, wherein the edge is beveled.
 27. A piece of cutmetal according to claim 25, wherein the edge is rounded.
 28. A piece ofcut metal according to claim 21, wherein said slag is disposed on thefirst surface and the second surface.
 29. A piece of cut metal accordingto claim 28, wherein the edge is beveled.
 30. A piece of cut metalaccording to claim 28, wherein the edge is rounded.
 31. A piece of cutmetal formed by a metal cutting apparatus, comprising: first and secondsurfaces; said first and second surfaces being disposed on oppositesides of said cut metal; an edge connecting said first and secondsurfaces, wherein said edge is not perpendicular to the first and secondsurfaces; and said cut metal has slag disposed in a generally arcuatemanner on at least one of said surfaces.
 32. A piece of cut metalaccording to claim 31, wherein the edge is rounded.
 33. A piece of cutmetal according to claim 31, wherein the edge is beveled.
 34. A piece ofcut metal according to claim 31, wherein the edge is wavy.
 35. A pieceof cut metal according to claim 31, wherein the edge is rounded, beveledand wavy.
 36. A piece of cut metal according to claim 31, wherein theedge is rounded and beveled and has an irregularity.
 37. A piece of cutmetal according to claim 31, wherein the edge is rounded and beveled andhas an arcuate grain.
 38. A piece of cut metal formed by a metal cuttingapparatus, comprising: first and second surfaces; said first and secondsurfaces being disposed on opposite sides of said cut metal; an edgeconnecting said first and second surfaces, wherein said edge is notperpendicular to the first and second surfaces; and said cut metal hasslag disposed in a generally arcuate manner on at least one surface thatis planar.
 39. A piece of cut metal according to claim 38, wherein theedge has generally no grain.